AN EXPERIMENTAL INVESTIGATION ON NANOSECOND LASER ABLATION OF SINGLE CRYSTALLINE SILICON WAFERS

This work investigates the occurrence of heat-affected zones and texture when performing laser machining and explores ways to reduce the prevalence of both. A reduced prevalence will lead to better performance of silicon wafers in nanotechnology within the semiconductor industry with fewer heat-affected zones (HAZs) and less surface texture. Varying parameters such as pulse energy, spot size, and scanning speed, created the conditions in which laser machining was performed on the silicon wafer sample. Data were collected at three different levels of each of the three different machining parameters (pulse energy, spot size, and scanning speed (active laser time are inversely related to counting as one parameter). 27 different combinations (conditions) were tested with each having three trials, and a total of 31 experiments were performed. It was found that laser pulse energy, spot size determined by the lens-to-sample distance and scanning speed influences the dimensions of the slots, heat affected zone (HAZ), and surface roughness of the slots. The results show that the range of laser pulse energy used in this study has not made significant influence on the ablation performance. Rather the spot size (lens-to-sample distances) played a major role in deciding both the dimensions, and HAZ of the features. Laser pulse energy has influenced the HAZ. Laser scanning speed has mostly influenced the surface roughness with higher scanning speed increasing the number of overlaps, thus increasing the average surface roughness. Understanding the effects of parameters for laser ablation of silicon wafer can be helpful to the semiconductor industry. This study aims to provide a plausible solution to the issue of heataffected zones and surface texture on silicon wafers that the semiconductor industry faces when manufacturing these wafers.